1. Field of the Invention
The present invention relates to an image pickup apparatus having an image pickup element such as a digital camera, and more specifically to an image pickup apparatus having a function of correction processing of a pixel defect of an image pickup element.
2. Description of the Related Art
In an image pickup element which is used in a digital camera, it is very difficult to prevent the pixel defect itself from being formed. In the meantime, there is an increasing need for measures against the pixel defect due to tendency toward larger number of pixels (increase in the number of defects) and tendency to more narrow a pixel pitch (increase in a defect ratio) in recent years. As characteristics required for the processing of the pixel defect, a high capability of processing a pixel defect and an appropriate processing load may be given for example.
Further, an apparatus (called a light field camera) that re-forms an image by obtaining lights passing through different pupil areas and uses the re-formed image as an output image has been suggested.
For example, Japanese Patent Application Laid-Open No. 2007-4471 (Patent Document 1) discloses a method of picking up an object image by using an image pickup element that is capable of individually receiving lights passing through different pupil areas, and creating an image whose focus is adjusted after image pickup.
Further, “CCD camera technology” written by Yasuo Takemura, Radio Technology Corporation (Non-Patent Document 1) discloses a method of interpolating the pixel defect (details of the pixel defect will be described below) in horizontal and vertical directions and in an inter-frame manner.
However, according to the related art disclosed in Patent Document 1 described above, when a pixel defect occurs in an image pickup element that forms an image pickup system for obtaining lights passing through different pupil areas, a proper image may not always be obtained.
In other words, in Patent Document 1, even though an image in which a focus position is changed after image pickup may be obtained, a method of obtaining an image excluding an influence of a defected portion in a case where a pixel defect is present is not disclosed. Further, in Non-Patent Document 1, since the interpolation processing is performed on the basis of simple image correlation, appropriate interpolation may not be performed on the image pickup element that forms an image pickup system of Patent Document 1.